Lubricating oil and lubrication therewith



Patented Dec. 13, 1938 UNITED s 'i'E s Pr .rrica Elmer William Cook, New York, N. Y.,

. Tide Water Associated Oil Company, onne,

N. .L, a corporation of Delaware No Drawing Application August 13, 1937, Serial No. 158,918

6 Claims. (01.81-9) a I This invention relates to lubricants intended for service in the lubrication of internal combustion engines. The invention more particularly is concerned with lubricating or motor oils of 5 mineral hydrocarbon origin which are normally corrosive toward bearing metal alloys of the character of cadmium-silver, cadmium-nickel or copper-lead, as well as those bearing metals of exceptionally high lead content (of the order of 75% to 99%) wherein minor proportions of alloying metals impart unusual hardness to the alloy; and has, for an important objective, the inhibition or prevention of deterioration of such bearing metal in service by the corrosive action 15 of the lubricant thereon.

Engine bearings comprising or surfaced with cadmium-silver, high-lead or like alloys now are frequently employed in lieuof the more usual Babbitt metal hearings, in order to cope 20 with extreme service conditions of friction and temperature. These conditions are the consequences of modern developments in internal combustion engines making available high sustained speeds and requiring bearings formed of metals 25 or alloys having greater resistance to wear, and further characterized by higher melting points necessary to prolonged life-under the extreme thermal conditions existing during operation of the engine. Temperatures at the bearing sur- 80 faces during operation are, or may be, much higher in the case of engines requiring these new.

bearings than formerly was the circumstance with engines in which Babbitt metal bearings gave satisfactory service.

Experience with bearings of the character or type exemplified by cadmium-silver, cadmiumnickel, copper-lead and high-lead alloys has demonstrated, however, that their utility is" greatly impaired by an extreme susceptibility to rapid 40 deterioration by the corrosive action or efiect of many available lubricating oils. Particularly has this efiect been noted when the oils are of the character generally regarded as superior lubricants by conventional criteria.

45 Little is known concerning the nature of the corrosive action or its causes; but in general its has been observed that motor oils derived from selected crudes predominantly paramnic in origin, as well as those oils from these or other 50 crudes which have been improved by treatment with selective solvents, exhibit a marked tendency toward corrosion of the bearings in ques-.

tion, although by other tokens the lubricant is of superior quality. Oxidation stability, as indi-- l cated by sludge or acid formation in conventional tests indicative of the tendency toward deterioration of the oil itself in service, does not appear to have reliable correlation with the tendency of the oil to corrode bearing surfaces. It is possible that the high bearing surface tempera- 5 tures existing under service conditions with the new bearings may be a factor in occasioning the observed deleterious effect of motor oils thereupon. It would appear, also, that the problem of bearing corrosion, with which the present invention is particularly concerned, contrasts with problems of lubricant deterioration per se, since oils characterized by long life and good stability in conventional tests may, and frequently do, prove to be the most corrosive in bearing corrol6 sion tests. No theory in explanation of the observed corrosive action or the prevention thereof, as herein proposed according to the invention, is intended to be relied upon.

According to the present invention, it has now been found that the corrosive effect of lubricating oils upon bearing surfaces of the character referred to above may be avoided in novel and'eflective manner by incorporating with such oils particular compounds having a retarding or inhibiting effect in respect of such corrosion. More specifically, the invention arises from the discovery that a compound comprising p-ethoxy phenyl morpholine efl'ects a very beneficial .retardation of the corrosive action of intemal-combustion engine lubricating oils upon cadmiumsilver, cadmium-nickel, copper-lead, high-lead and like bearing metal alloys.

It is, therefore, an important object of the present invention to inhibit or retard the cor- 3 rosive deterioration of these and like bearingmetal alloys in automotive service by providing a lubricant therefor comprising a refined mineral hydrocarbon oil having incorporated therewith p-ethoxy phenyl morpholine in small but eifec- 40 tive proportion. Likewise, it is an object of the invention to improve, and to prepare improved, motor oils of petroleum origin by incorporating therein p-ethoxy phenyl morpholine in corrosion inhibiting proportions. The provision of an inhibitor effective for such purpose and comprising a compound as aforementioned naturally is a major objective. Viewed in another aspect, the invention may be regarded as encompassing a novel method of lubricating bearing metal surfaces, of the character of cadmium-silver, cadmium-nickel, copperlead, high-lead or like alloys, by applying thereto a film of lubricant comprising a mineral hydrocarbon oil having incorporated therewith a small but efiective proportion of p-ethoxy phenyl morpholine. With this method of lubrication it has been found that prolonged life and consequent improved service may be attained in the use of 'these alloys as bearing metals of internal combustion engines, particularly when operating conditions such as high sustained speeds under load occasion unusually high bearing surface temperatures. Ordinarily, the oil selected for use, in applying the lubricating method of the invention to its intended service, will be of a character generally regarded as of superior grade and refining. Thus, the invention finds particular utility in making possible the beneficial use of such oils by avoiding deleterious consequences otherwise encountered when no preventive measures are taken against the corrosive deterioration of bearing metal alloys as hereinbefore referred to. It will be understood, however, that the invention contemplates no limitation inthis respect, and that the method of lubrication herein described may be practiced in conjunction with mineral hydrocarbon lubricating oils taken as a broad class and regardless of origin.

P-ethoxy phenyl morpholin'e is a compound conforming to the structural formula CHr-CH:

o \NOOCQHE cnrom and is very readily soluble in mineral hydrocarbon oil. Conveniently, the compound p-ethoxy phenyl morphoiine may be prepared by reacting beta-beta di-chlor ethyl ether with p-phenetidine in the presence of magnesium oxide and a small amount of water. The proportion of p-ethoxy phenyl morpholine necessary to-accomplish the objects of the present invention. is quite small, percentages of the order of 0.2% by weight of the compound dissolved in motor' oil exhibiting a marked inhibiting effect. In, view of the ready solubility of this compound in general lubricating oils, it may be preferred, however, to practice the invention by dissolving a relatively large proportion of p-ethoxy phenyl morpholine (for example several percent) in motor oil of the character contemplated for use; and then adding suitable proportions of the thus formed concentrate to both quantities of oil. the illustrative tests reported hereinafter the inhibitor of the invention was used in proportions of 0.2% by weight, but. the said percentage is not intended as a limitation upon the contemplated scope and practice of the invention, as obviously the inhibitor may be, and is intended to be, employed in any corrosion inhibiting proportion.

The tendency of motor oils to corrode bearings of the, character in question may be determined by a convenient test which affords a ready method of obtaining a comparative evaluation of motor oils in the laboratory. In this test method a group of bearings, ordinarily including at least one each of several of the newer bearing metal alloys viz.: cadmium-silver, cadmium-nickel and copper-lead) is supported in a chamber in which air may circulate and the bearing surfaces are exposed for a period of 22 hours to a stream of oil sprayed under pressure continuously upon the corrodible area. The oil is maintained at a temperature of approximately 335" F. and the spray is so directed as to disperse the oil over the surfaces of the bearings. Means are provided for recirculating the sprayed oil so that a. given quantity is used for a given test, thus simulating service conditions in an engine. The measure of corrosion is taken as the loss in weight of the bearing per unit of exposed corrodible surface.

The test method described above is carried out in the familiar Underwood corrosion apparatus supplied by the Scientific Instrument Company of Detroit, Michigan, in accordance with General Motors specifications.

Results obtained utilizing the foregoing test for comparative evaluation of motor oils with and without an inhibitor according to the invention provide specific illustration of the value and in hibiting effectiveness of p-ethoxy phenyl morpholine. The oil used for the test was an S. A. E. 20 motor oil comprising a blend of well refined paraflinic base stocks and having an A. P. I. gravity of 30.1, Saybolt viscosity F. of about 300 seconds, Saybolt viscosity 210 F. of 54 seconds and flash point of 425 F. Inhibitor, when added, was used in an amount of 0.2% by weight based on the oil. During each run cadmium-silver, cadmium-nickel and copper-lead bearings all were present; and comparative losses in weight per square decimeter due to corrosion were observed as follows for the respective bearings:

Oiltglus on p-e ox Bearing pheny blank morph? line Grams Cadmium-silver 4. 6 No loss. Cadmium-nickel. 6. 5 Do. Copper-lead 1.4 Do.

While the utility of the invention has been illustrated specifically with reference to a particular motor oil, no limitation is to be inferred therefrom, and other oils, whether or not comparable in specification or origin, may be used in the lubrication of bearings of the type described in internal combustion engines, which bearing surfaces have substantially the corrosion susceptibility characterizing cadmium-silver, cadmium-nickel and copper-lead alloys, which consists in applying to said bearing surfaces lubricant comprising mineral hydrocarbon oil normally tending to corrode said surfaces and having incorporated therein corrosion inhibiting proportions of p-ethoxy phenyl morpholine.

3. In the lubrication of bearing surfaces haying substantially the corrosion susceptibility characterizing cadmium-silver, cadmium-nickel and copper-lead alloys, with mineral hydrocarbon oil normally tending to cause substantial and rapid corrosion thereof, the method of inhibiting such corrosion, which comprises incorporating with said oil corrosion inhibiting proportions of p-ethoxy phenyl morpholine.

4. A lubricant for the lubrication of internal jcombustion engines operating at high sustained ing surfaces of an alloy selected from the class of cadmium-silver, cadmium-nickel and copperlead alloys, which comprises a well refined mineral lubricating oil of the character normally effective to cause substantial corrosion of such bearing surfaces, and added p-ethoxy phenyl morpholine in corrosion inhibiting proportions.

5. Mineral oil composition, comprising a hydrocarbon lubricating oil of motor oil character normally tending to corrode bearing metals having substantially the corrosion susceptibility characterizing cadmium-silver, cadmium-nickel and copper-lead alloys when continuously applied to the surface thereof for an extended 

